1. Field of the invention:
This invention relates to a one-way reducing and enlarging printer (or one-way variable magnification printer) which enlarges or reduces an image of film only in one direction for printing on photosensitive materials. Prior arts:
One-way (or unidirectional) variable magnification printers are ordinarily necessary to correct extension in peripheral direction at rotary press printing or to adjust the shrinkage allowance for plate making process or printing process.
The Official Gazzette of U.S. Pat. No. 3,445,165 discloses a photograph deforming device for slit exposure by a link driving system which moves a negative and photosensitive material placed under the exposure slit at different speed and in the same direction (perpendicular to the slit).
The Official Gazzette of Japanese Patent Publication (examined) No. Sho. 57-1825 also discloses a one-way reducing and enlarging plate making (graphic arts) device equipped with a first roller to feed negative films and a second roller to feed photosensitive films, in which the negative films and the photosensitive films are subjected to linear contact at a part of the circumference of the second roller, and the first and the second rollers are turned at different speeds for slit exposure.
By the photograph deforming device disclosed in the Official Gazzette of U.S. Pat. No. 3,445,165, the negative and photosensitive material are connected by a link driving system. Accordingly, the accuracy is limited to a certain degree because of flexibility of the link and mechanical errors in manufacturing.
By the one-way reducing and enlarging plate making device stated in the Official Gazzette of Japanese Patent Publication (examined) No. Sho. 57-1825, on the other hand, the rate of revolution (or rotational frequency) of both rollers can not be changed freely. It is accordingly necessary to adjust exposure of the photosensitive material by the light controller of the light source lamp and not by the rate of revolution of the rollers (i.e. the exposing time). However, accurate control of exposure is difficult since it is almost impossible to change intensity of the light source lamp without changing the color temperature.